scholarly journals Effect of leaf Water potential on cold tolerance of Coffea arabica L.

2002 ◽  
Vol 45 (4) ◽  
pp. 439-443 ◽  
Author(s):  
Lázara Pereira Campos Caramori ◽  
Paulo Henrique Caramori ◽  
João Manetti Filho
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Coffea Arabica ◽  
Experimental Period ◽  
Leaf Water ◽  
Regional Variability ◽  
Wide Range ◽  
Coffee Plants ◽  
Coffea Arabica L ◽  
Severe Leaf

Young coffee plants from cultivar Mundo Novo of Coffea arabica were grown without irrigation for 32 consecutive days, to evaluate the effect of leaf water potential on damage caused by low temperatures, under controlled conditions. A wide range of leaf water potentials were evaluated, from - 0.45MPa (wet soil) at the beginning of the experimental period, to - 4.8MPa (severe leaf wilting) at the end. Results showed that under moderate water stress, there was a higher frequency of undamaged plants and lower frequency of severely damaged plants. These results help explain part of the regional variability observed after a frost and stress the importance of new studies associating cold and drought tolerance in coffee.

Evaluation of the hydraulic press for measurement of leaf water potentials in cassava

1983 ◽  
Vol 101 (2) ◽  
pp. 407-410 ◽  
Author(s):  
J. A. Palta
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Hydraulic Press ◽  
Pressure Chamber ◽  
Leaf Water ◽  
Moisture Loss ◽  
Total Leaf Area ◽  
Water Potentials ◽  
Wide Range ◽  
Poor Relationship

SUMMARYIn the application of the Scholander pressure chamber technique to cassava water relations studies, the leaf water potential measured on central lobules was initially compared with that measured on entire leaves (including petiole). Measurements made using both a Campbell-Brewster hydraulic press and a pressure chamber of the leaf water potential in six different cassava clones were also compared. Although the central lobules showed a greater sensitivity to moisture loss after sampling than entire leaves, their leaf water potential was in close agreement with those measured on the entire leaves (r3 = 0·96). Therefore, for routine and field estimates in cassava, measurements made on the central lobules may be used to avoid the large reduction in total leaf area. The Campbell-Brewster hydraulic press satisfactorily estimated leaf water potential in M.Col. 1684 clone, which had the longest and narrowest lobules, but in other clones the leaf water potential was overestimated at high leaf potential (> -12·5) and underestimated at low water potentials (< -12·5). Over a wide range of leaf water potentials, a poor relationship between leaf water potentials estimated with hydraulic press and with the pressure chamber was observed for cassava because press estimates are influenced by lobule length and lobule width.

New plant hydraulic architecture reproduces impacts of droughts in the Amazon rainforest

2021 ◽  
Author(s):  
Phillip Papastefanou ◽  
Christian Zang ◽  
Thomas Pugh ◽  
Daijun Liu ◽  
David Lapola ◽  
...  
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Leaf Water ◽  
Amazon Rainforest ◽  
Hydraulic Architecture ◽  
Vegetation Model ◽  
Dynamic Global Vegetation Model ◽  
Plant Hydraulics ◽  
Wide Range ◽  
Carbon Losses

&lt;p&gt;The Amazon rainforest has been hit by extreme drought events in recent decades. Thereby, plant hydraulics are essential to better understand the impacts of droughts on single plants and whole forest ecosystems. Plant hydraulic mechanisms such as stomatal closure and leaf water potential are very complex, still posing challenges for current vegetation model development and parameterization. Here, we present the new hydraulic architecture of the Dynamic Global Vegetation Model LPJ-GUESS, accounting for leaf stomatal responses to plant water status and subsequent drought-induced mortality. We show that when applying the model to the Amazon rainforest we can reproduce the observed increasing trend in carbon losses and the decreasing trend in net carbon sink from plot observations over the past two decades. Our model simulations suggest that the increasing historical trend in carbon losses from mortality can be explained by hydraulic failure and associated mortality.&lt;/p&gt;&lt;p&gt;The high biodiversity of the Amazon tropical rainforest poses further challenges for process-based models. Here we present an approach to include the diversity of plant responses to drought by simulating 37 individual Plant Functional Types (PFTs) differing in their leaf water potential regulation- and resistance to soil water stress, and provide a simple solution how to cover a wide range of species and species-specific parameters. Future modelling studies should also take species interaction and competition of different hydraulic strategies into account.&lt;/p&gt;

scholarly journals Water relations and organic solutes production in four umbu tree (Spondias tuberosa) genotypes under intermittent drought

2009 ◽  
Vol 21 (1) ◽  
pp. 43-53 ◽  
Author(s):  
Elizamar C. Silva ◽  
Rejane J. M. C. Nogueira ◽  
Fernando H. A. Vale ◽  
Natoniel F. de Melo ◽  
Francisco P. de Araújo
Keyword(s):  
Amino Acids ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Stomatal Closure ◽  
Experimental Period ◽  
Great Variability ◽  
Leaf Water ◽  
Organic Solutes ◽  
Solute Accumulation ◽  
Water Treatments

In order to evaluate changes in leaf water potential (ψw) and solute accumulation induced by intermittent drought, an research was performed under greenhouse conditions using four umbu tree genotypes (GBU 44, GBU 48, GBU 50 and GBU 68) and two water treatments (control and stressed by withholding water), with four replicates. The ψw was measured in four-hour intervals during a 24-hour period at the first stomatal closure and at the end of the experimental period. Carbohydrates, amino acids, protein and proline contents were also evaluated in leaves and roots. Significant differences were found in most of the studied parameters. The lower ψw hour was between 800 h and 1200 h. GBU 50 reduced significantly ψw in stressed plants at 800 h, while control plants reduced at 1200 h . GBU 68 presented the higher ψw. The extending of the stress induced reductions to carbohydrates in the leaves of all genotypes, increases in amino acids to GBU 44 and 48, and reductions of 40% and 43% to GBU 50 and 68, respectively; results also showed alterations in proline content. In the roots, increases in carbohydrates were observed only in GBU 48. Alterations in amino acids, protein, and proline were verified. Umbu trees presented isohydric behavior maintaining high leaf water potential and a great variability in organic solutes accumulation in response to drought with marked differences among the genotypes.

Photosynthesis in Coffea arabica. II. Effects of Water Stress

1980 ◽  
Vol 16 (1) ◽  
pp. 21-27 ◽  
Author(s):  
D. Kumar ◽  
Larry L. Tieszen
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Coffea Arabica ◽  
Water Status ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Plant Water

SUMMARYExperiments were carried out to relate soil moisture to leaf water potential (Ψ1), and to determine the effects of varying Ψ1, on leaf conductances and photosynthesis in coffee. Stomatal conductance was maximum at 0900 h, but plants growing in drier soil showed marked mid-day stomatal closure. After 1500 h, stomata began closing although plant water status improved. Photosynthesis in relation to changing Ψ1 appeared to exhibit roughly three different rates. At the fixed experimental temperature (25°C) low Ψ1 reduced photosynthesis throughits influence on stomata, but under field conditions low Ψ1 and an accompanying rise in temperature could lower the rate by lowering both mesophyll and stomatal conductances.

scholarly journals Brachiaria decumbens supresses the initial growth of Coffea arabica

2004 ◽  
Vol 61 (6) ◽  
pp. 579-583 ◽  
Author(s):  
Guilherme Faus da Silva Dias ◽  
Pedro Luís da Costa Aguiar Alves ◽  
Tomás Carneiro de Souza Dias
Keyword(s):  
Coffea Arabica ◽  
Plant Density ◽  
Growth Period ◽  
Experimental Period ◽  
Initial Growth ◽  
Brachiaria Decumbens ◽  
Asbestos Cement ◽  
Sensitive Characteristics ◽  
Coffee Plants ◽  
Coffea Arabica L

Brachiaria decumbens is becoming one the most common weeds growing in young coffee orchards because, besides its fast growth and difficulty of control, new coffee orchards are usually established in pasture areas. In order to verify the effect of B. decumbens plant density on the early growth of coffee (Coffea arabica L. cv. Catuaí Amarelo), a competition experiment was conducted under semi-controlled humidity conditions. Soil collected in a Typic Haplustox was placed in 70 L asbestos cement boxes and one coffee seedling was planted in each box. The B. decumbens seedlings were transplanted to the boxes at the 2-4 leaf stage. Treatments consisted of 0, 4, 8, 12, 16, 20, 24, 36, 48, and 60 weeds m-2. The experimental period started 120 days after transplanting and the experimental design was organized as completely randomized blocks, with four replicates. All coffee plant parameters evaluated were negatively affected by the interference. The most sensitive characteristics were leaf area (41.8% reduction with 8 plants m-2, reaching 68.7% at a density of 60 plants m-2). Therefore, at a density of 8 plants m-2 the reduction in leaf dry biomass was 41.4% compared with the check. At the density of 60 plants m-2 it was 72.8%. B. decumbens, at a density of 8 or more plants m-2, suppressed coffee plants during a growth period of 120 days.

Changes in Diffusive Conductance and Water Potential of Wheat Plants Before and After Anthesis

1977 ◽  
Vol 4 (1) ◽  
pp. 75 ◽  
Author(s):  
JM Morgan
Keyword(s):  
Water Potential ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
Leaf Water ◽  
Wide Range ◽  
Before And After ◽  
Relative Water ◽  
Complete Failure ◽  
Two Phases ◽  
The Relationship

The relationships between stomatal conductance and leaf water potential, ΨL, of wheat plants during drying under controlled conditions showed three phases: (1) no apparent effect until ΨL reached about - 1.8 J g-1; (2) increasing closure as ΨL decreased to about - 3 J g-1; and (3) complete failure to open at lower ΨL values. At any given water potential in the first two phases, the stomata were always more open during the post-anthesis stage than during the pre-anthesis stage. Although the relationship between leaf water potential and relative water content differed with growth stage, this was not important in the overall plant response to a water deficit. Over a wide range of ΨL, the conductance of the adaxial surface was less variable and more sensitive than that of the abaxial surface. The ratio of these conductances was very variable and followed no discernible pattern. The water potential of spikelets was appreciably higher than that of flag leaves, especially at low values of the latter. Both organs died at about the same water potential (about -4 J g-1); hence, spikelets survived longer periods of water deficit than leaves. These responses are discussed in respect of sensitivity of grain yield to the stage of growth at which a water deficit is experienced and to the phenomenon of spikelet death. Differences between three cultivars examined were small.

Comparisons between Press and Pressure Chamber Techniques for Measuring Leaf Water Potential

1981 ◽  
Vol 17 (1) ◽  
pp. 75-84 ◽  
Author(s):  
T. M. Yegappan ◽  
B. J. Mainstone
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Elaeis Guineensis ◽  
Water Status ◽  
High Water ◽  
Hydraulic Press ◽  
Pressure Chamber ◽  
Leaf Water ◽  
Wide Range ◽  
The Press

SUMMARYA hydraulic press (the J-14) was compared with a Scholander pressure chamber to measure leaf water potential in Theobroma cacao, Gliricidia maculata, Cajanus cajan and Elaeis guineensis. Although the press satisfactorily estimated water status in soft, unhardened leaves of T. cacao, G. maculata and C. cajan at high water potential, it underestimated water status in hardened leaves of T. cacao. Satisfactory estimates were obtained at low water potential for hardened leaves of T. cacao but not for the others. There was a poor relation between readings of the two instruments for E. guineensis over a wide range of water potentials because press readings appeared to be influenced by leaf structure.

scholarly journals 327 LEAF WATER POTENTIAL, RELATIVE WATER CONTENT AND GAS EXCHANGE OF STRAWBERRY LEAVES IN RESPONSE TO WATE.R STRESS

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 477d-477
Author(s):  
Chuhe Chen ◽  
J. Scott Cameron ◽  
Ann Marie VanDerZanden
Keyword(s):  
Gas Exchange ◽  
Water Potential ◽  
Water Content ◽  
Leaf Water Potential ◽  
Relative Water Content ◽  
Leaf Age ◽  
Leaf Water ◽  
Derivative Spectra ◽  
Wide Range ◽  
Relative Water

Leaf water potential (LWP). relative water content (RWC), gas exchange rates and 4th-derivative spectra were measured in water-stressed and normally Irrigated plank of Totem' strawberry (Fragaria × ananassa) grown in a growth chamber. CO2 assimilation rate (A) dropped sharply when LWP decreased from -0.5 to -1.2 MPa and almost ceased as LWP fell below -1.5 MPa. There was a significant but more gradual decline of A as RWC decreased form 90% to 55%. An exponential relationship with A was observed across a wide range of LWP and RWC (Rz= 0.64, 0.86, respectively). LWP was more closely related with transpiration and leaf and stomatal conductances than with A and water use efficiency. RWC was highly correlated with all gas exchange parameters. Under moderate water stress, younger leaves maintain higher RWC and A than older leaves. There was no relationship between LWP and leaf age. RWC and A were both negatively correlated with peak amplitudes of Ca 684 and Ca 697 and positively correlated with Ca 693 in their 4th-derivative spectra of chlorophyll. LWP had a negative correlation with Cb 640.

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